Georgia

R402.1.2.1 (N1102.1.2.1) Indirectly conditioned attics.

Where table N1102.1.2 (R402.1.2) requires R38 or Table N1102.1.4 (R402.1.4) requires a U-factor of 0.030, an air impermeable insulation installed to the underside or directly above the roof deck with a U-factor of 0.05 or R-value of R-20 shall be deemed equivalent to the provisions in N1102.2.1 (R402.2.1), with the following requirements:

• The house shall attain a blower door test result < 3 ACH50
• The house shall require a whole house mechanical ventilation system that does not solely rely on a negative pressure strategy (must be positive, balanced or hybrid)
• Where insulation is installed below the roof deck and the exposed portion of roof rafters are not already covered by the R-20 depth of the air-impermeable insulation, the exposed portion of the roof rafters shall be wrapped (covered) by minimum R-3 unless directly covered by drywall / finished ceiling. Roof rafters are not required to be covered by minimum R-3 if a continuous insulation is installed above the roof deck.
• Indoor heating, cooling and ventilation equipment (including ductwork) shall be inside the building thermal envelope.

Citation: Georgia State Supplements and Amendments to the International Energy Conservation Code (2022)